This invention relates to a method for manufacturing graphite whiskers, and more particularly to a method for manufacturing graphite whiskers from organic compounds having a condensed polycyclic structure.
The prior art processes of manufacturing graphite whiskers may be broadly classified into two types. One of them reported by Roger Bacon consists in depositing graphite whiskers by means of a dc arc at high temperature and pressure (Journal of Applied Physics 31, 283 to 290, 1960). According to this report, graphite whiskers 1 to 5 microns in diameter and about 3 cm long were grown in a dc arc derived from graphite electrodes at a temperature of about 3700.degree. K in an atmosphere of argon at 92 atm. The graphite whiskers had such physical properties as high flexibility, tensile strength of 2100 kg/mm.sup.2 at maximum, modulus of elasticity of 7.1 .times. 10.sup.4 kg/mm.sup.2 and specific resistance of 60 to 76 .mu.ohm -- cm. Although each graphite whisker was not a single crystal formation in a strict sense, the crystals of the graphite whisker were arranged in the form of a single continuous sheet rolled up like a scroll or a plurality of separate sheets rolled up in concentrical relationship, the c-axis of the crystals being orientated exactly perpendicular to the fiber axis. However, this process was accompanied with various unsettled difficult problems with respect to the manufacturing apparatus and the operation thereof. The process, therefore, was far short of the object of industrial mass production and still remained in an experimental stage.
The other type of prior art processes which has already been reported by many researchers, for example, U.S. Pat. No. 3,378,345, consisted in depositing carbon fibers in a gas phase by thermally decomposing hydrocarbon gases having a relatively low molecular weight (which are outside of the high molecular weight condensed polycyclic compounds employed in this invention). Although some reports referred to the carbon fibers obtained as graphite whiskers, said fibers were actually of nearly the same grade as those commercially available at present, as judged from data on the various physical properties. For example, the reported fibers had a tensile strength equal to about one-fifth of that of the graphite whiskers experimentally formed by Roger Bacon, and as high a specific electric resistivity in the direction of the fiber axis as scores of times that of true graphite whiskers.